feat: Rust port of Claude Code CLI

Crates:
- api: Anthropic Messages API client with SSE streaming
- tools: Claude-compatible tool implementations (Bash, Read, Write, Edit, Glob, Grep + extended suite)
- runtime: conversation loop, session persistence, permissions, system prompt builder
- rusty-claude-cli: terminal UI with markdown rendering, syntax highlighting, spinners
- commands: subcommand definitions
- compat-harness: upstream TS parity verification

All crates pass cargo fmt/clippy/test.

rust/crates/runtime/src/json.rs

@@ -0,0 +1,358 @@
+use std::collections::BTreeMap;
+use std::fmt::{Display, Formatter};
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum JsonValue {
+    Null,
+    Bool(bool),
+    Number(i64),
+    String(String),
+    Array(Vec<JsonValue>),
+    Object(BTreeMap<String, JsonValue>),
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct JsonError {
+    message: String,
+}
+
+impl JsonError {
+    #[must_use]
+    pub fn new(message: impl Into<String>) -> Self {
+        Self {
+            message: message.into(),
+        }
+    }
+}
+
+impl Display for JsonError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.message)
+    }
+}
+
+impl std::error::Error for JsonError {}
+
+impl JsonValue {
+    #[must_use]
+    pub fn render(&self) -> String {
+        match self {
+            Self::Null => "null".to_string(),
+            Self::Bool(value) => value.to_string(),
+            Self::Number(value) => value.to_string(),
+            Self::String(value) => render_string(value),
+            Self::Array(values) => {
+                let rendered = values
+                    .iter()
+                    .map(Self::render)
+                    .collect::<Vec<_>>()
+                    .join(",");
+                format!("[{rendered}]")
+            }
+            Self::Object(entries) => {
+                let rendered = entries
+                    .iter()
+                    .map(|(key, value)| format!("{}:{}", render_string(key), value.render()))
+                    .collect::<Vec<_>>()
+                    .join(",");
+                format!("{{{rendered}}}")
+            }
+        }
+    }
+
+    pub fn parse(source: &str) -> Result<Self, JsonError> {
+        let mut parser = Parser::new(source);
+        let value = parser.parse_value()?;
+        parser.skip_whitespace();
+        if parser.is_eof() {
+            Ok(value)
+        } else {
+            Err(JsonError::new("unexpected trailing content"))
+        }
+    }
+
+    #[must_use]
+    pub fn as_object(&self) -> Option<&BTreeMap<String, JsonValue>> {
+        match self {
+            Self::Object(value) => Some(value),
+            _ => None,
+        }
+    }
+
+    #[must_use]
+    pub fn as_array(&self) -> Option<&[JsonValue]> {
+        match self {
+            Self::Array(value) => Some(value),
+            _ => None,
+        }
+    }
+
+    #[must_use]
+    pub fn as_str(&self) -> Option<&str> {
+        match self {
+            Self::String(value) => Some(value),
+            _ => None,
+        }
+    }
+
+    #[must_use]
+    pub fn as_bool(&self) -> Option<bool> {
+        match self {
+            Self::Bool(value) => Some(*value),
+            _ => None,
+        }
+    }
+
+    #[must_use]
+    pub fn as_i64(&self) -> Option<i64> {
+        match self {
+            Self::Number(value) => Some(*value),
+            _ => None,
+        }
+    }
+}
+
+fn render_string(value: &str) -> String {
+    let mut rendered = String::with_capacity(value.len() + 2);
+    rendered.push('"');
+    for ch in value.chars() {
+        match ch {
+            '"' => rendered.push_str("\\\""),
+            '\\' => rendered.push_str("\\\\"),
+            '\n' => rendered.push_str("\\n"),
+            '\r' => rendered.push_str("\\r"),
+            '\t' => rendered.push_str("\\t"),
+            '\u{08}' => rendered.push_str("\\b"),
+            '\u{0C}' => rendered.push_str("\\f"),
+            control if control.is_control() => push_unicode_escape(&mut rendered, control),
+            plain => rendered.push(plain),
+        }
+    }
+    rendered.push('"');
+    rendered
+}
+
+fn push_unicode_escape(rendered: &mut String, control: char) {
+    const HEX: &[u8; 16] = b"0123456789abcdef";
+
+    rendered.push_str("\\u");
+    let value = u32::from(control);
+    for shift in [12_u32, 8, 4, 0] {
+        let nibble = ((value >> shift) & 0xF) as usize;
+        rendered.push(char::from(HEX[nibble]));
+    }
+}
+
+struct Parser<'a> {
+    chars: Vec<char>,
+    index: usize,
+    _source: &'a str,
+}
+
+impl<'a> Parser<'a> {
+    fn new(source: &'a str) -> Self {
+        Self {
+            chars: source.chars().collect(),
+            index: 0,
+            _source: source,
+        }
+    }
+
+    fn parse_value(&mut self) -> Result<JsonValue, JsonError> {
+        self.skip_whitespace();
+        match self.peek() {
+            Some('n') => self.parse_literal("null", JsonValue::Null),
+            Some('t') => self.parse_literal("true", JsonValue::Bool(true)),
+            Some('f') => self.parse_literal("false", JsonValue::Bool(false)),
+            Some('"') => self.parse_string().map(JsonValue::String),
+            Some('[') => self.parse_array(),
+            Some('{') => self.parse_object(),
+            Some('-' | '0'..='9') => self.parse_number().map(JsonValue::Number),
+            Some(other) => Err(JsonError::new(format!("unexpected character: {other}"))),
+            None => Err(JsonError::new("unexpected end of input")),
+        }
+    }
+
+    fn parse_literal(&mut self, expected: &str, value: JsonValue) -> Result<JsonValue, JsonError> {
+        for expected_char in expected.chars() {
+            if self.next() != Some(expected_char) {
+                return Err(JsonError::new(format!(
+                    "invalid literal: expected {expected}"
+                )));
+            }
+        }
+        Ok(value)
+    }
+
+    fn parse_string(&mut self) -> Result<String, JsonError> {
+        self.expect('"')?;
+        let mut value = String::new();
+        while let Some(ch) = self.next() {
+            match ch {
+                '"' => return Ok(value),
+                '\\' => value.push(self.parse_escape()?),
+                plain => value.push(plain),
+            }
+        }
+        Err(JsonError::new("unterminated string"))
+    }
+
+    fn parse_escape(&mut self) -> Result<char, JsonError> {
+        match self.next() {
+            Some('"') => Ok('"'),
+            Some('\\') => Ok('\\'),
+            Some('/') => Ok('/'),
+            Some('b') => Ok('\u{08}'),
+            Some('f') => Ok('\u{0C}'),
+            Some('n') => Ok('\n'),
+            Some('r') => Ok('\r'),
+            Some('t') => Ok('\t'),
+            Some('u') => self.parse_unicode_escape(),
+            Some(other) => Err(JsonError::new(format!("invalid escape sequence: {other}"))),
+            None => Err(JsonError::new("unexpected end of input in escape sequence")),
+        }
+    }
+
+    fn parse_unicode_escape(&mut self) -> Result<char, JsonError> {
+        let mut value = 0_u32;
+        for _ in 0..4 {
+            let Some(ch) = self.next() else {
+                return Err(JsonError::new("unexpected end of input in unicode escape"));
+            };
+            value = (value << 4)
+                | ch.to_digit(16)
+                    .ok_or_else(|| JsonError::new("invalid unicode escape"))?;
+        }
+        char::from_u32(value).ok_or_else(|| JsonError::new("invalid unicode scalar value"))
+    }
+
+    fn parse_array(&mut self) -> Result<JsonValue, JsonError> {
+        self.expect('[')?;
+        let mut values = Vec::new();
+        loop {
+            self.skip_whitespace();
+            if self.try_consume(']') {
+                break;
+            }
+            values.push(self.parse_value()?);
+            self.skip_whitespace();
+            if self.try_consume(']') {
+                break;
+            }
+            self.expect(',')?;
+        }
+        Ok(JsonValue::Array(values))
+    }
+
+    fn parse_object(&mut self) -> Result<JsonValue, JsonError> {
+        self.expect('{')?;
+        let mut entries = BTreeMap::new();
+        loop {
+            self.skip_whitespace();
+            if self.try_consume('}') {
+                break;
+            }
+            let key = self.parse_string()?;
+            self.skip_whitespace();
+            self.expect(':')?;
+            let value = self.parse_value()?;
+            entries.insert(key, value);
+            self.skip_whitespace();
+            if self.try_consume('}') {
+                break;
+            }
+            self.expect(',')?;
+        }
+        Ok(JsonValue::Object(entries))
+    }
+
+    fn parse_number(&mut self) -> Result<i64, JsonError> {
+        let mut value = String::new();
+        if self.try_consume('-') {
+            value.push('-');
+        }
+
+        while let Some(ch @ '0'..='9') = self.peek() {
+            value.push(ch);
+            self.index += 1;
+        }
+
+        if value.is_empty() || value == "-" {
+            return Err(JsonError::new("invalid number"));
+        }
+
+        value
+            .parse::<i64>()
+            .map_err(|_| JsonError::new("number out of range"))
+    }
+
+    fn expect(&mut self, expected: char) -> Result<(), JsonError> {
+        match self.next() {
+            Some(actual) if actual == expected => Ok(()),
+            Some(actual) => Err(JsonError::new(format!(
+                "expected '{expected}', found '{actual}'"
+            ))),
+            None => Err(JsonError::new(format!(
+                "expected '{expected}', found end of input"
+            ))),
+        }
+    }
+
+    fn try_consume(&mut self, expected: char) -> bool {
+        if self.peek() == Some(expected) {
+            self.index += 1;
+            true
+        } else {
+            false
+        }
+    }
+
+    fn skip_whitespace(&mut self) {
+        while matches!(self.peek(), Some(' ' | '\n' | '\r' | '\t')) {
+            self.index += 1;
+        }
+    }
+
+    fn peek(&self) -> Option<char> {
+        self.chars.get(self.index).copied()
+    }
+
+    fn next(&mut self) -> Option<char> {
+        let ch = self.peek()?;
+        self.index += 1;
+        Some(ch)
+    }
+
+    fn is_eof(&self) -> bool {
+        self.index >= self.chars.len()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{render_string, JsonValue};
+    use std::collections::BTreeMap;
+
+    #[test]
+    fn renders_and_parses_json_values() {
+        let mut object = BTreeMap::new();
+        object.insert("flag".to_string(), JsonValue::Bool(true));
+        object.insert(
+            "items".to_string(),
+            JsonValue::Array(vec![
+                JsonValue::Number(4),
+                JsonValue::String("ok".to_string()),
+            ]),
+        );
+
+        let rendered = JsonValue::Object(object).render();
+        let parsed = JsonValue::parse(&rendered).expect("json should parse");
+
+        assert_eq!(parsed.as_object().expect("object").len(), 2);
+    }
+
+    #[test]
+    fn escapes_control_characters() {
+        assert_eq!(render_string("a\n\t\"b"), "\"a\\n\\t\\\"b\"");
+    }
+}